This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. During the reporting period, we explored the role of polymorphisms in the vole V1aR gene in regulating gene expression and social behavior. We successfully created 3 knock-in mouse lines in which we replaced the mouse vasopressin receptor gene with one of three variants of the vole vasopressin receptor, each with different microsatellite polymorphisms. We continued a selective breeding program to create a line of prairie voles that differ in terms of their affiliative behavior and are now in our 5th generation. Finally, we developed the technology to create germ-line transgenic voles. These studies have important implications for understanding the mechanisms underlying social cognition disruptions in psychiatric disorders such as autism.